Catheter-type instrument



June 7, 1949. L. H. KRIPPENDol-RF 2,472,483

CATHETER-TYPE INSTRUMENT Original Filed May 5, 1944 Patented June 7, 1949 UNITED STATiS TNT OFFICE CATHETER-TYPE INSTRUMENT Louis H. Krippendorf, White Plains, N. Y., as-

signor to American Catheter Corporation, Port Chester, N. Y., a corporation of New York (Cl. 13S-49) 2 Claims.

This application is a. division of my co-pending application, Serial No. 534,207, filed May 5, 1944, now Patent No. 2,437,542.

The invention relates generally to surgical instruments and has particular reference to catheter-type instruments.

By the term catheter-type instrument, as used herein and in the appended claims, I intend to refer to the well-known kind f -device which is inserted endwse into and through constricted body channels for diagnostic, therapeutic and allied purposes. Illustrative of such instruments are ureteral and urethral catheters, bougies, liforms, and the like.

.A conventional instrument of this type is of elongated character and has a uniform over-all flexibility coupled with suicient rigidity to permit its endwise advancement. This paradoxical requirement for both flexibility and rigidity has heretofore presented a peculiar problem to the manufacturer. For example, in the case oi a ureteral catheter, it must be of sufficient ilexibility to `permit. the tip of the instrument to advance harmlessly through the constricted ureteral canal and readily to follow the curvatures encountered, yet as the ilexibility is increased by the manufacturer to meet this requirement, the body portion loses some of the rigidity necessari7 to enable the operator to elTect the desired advancement by endwise pressure exerted upon the rear end of the instrument. Similarly, in the case of bougies or the like, it may under certain circumstances be desirable to increase the rigidity of the tip portion, yet the instrument as a whole may thereby become too iniiexible to follow an irregularly curved path with adequate ease.

The principal object of my present invention is directed toward a solution of this problem, and my invention is predicated upon the discovery that a catheter-type instrument may be caused to embody diierent flexibilities along its longitudinal axis without materially altering its basic structural nature or impairing the other inherent qualities which it necessarily must possess.

This desirable and advantageous result is achieved in an entirely practical and commercially-feasible manner.

In accordance with one conventional manufacturing procedure, the construction of a cathetertype instrument involves the formation of an initially limp fabric base of intertwined threads, this case being usually rst impregnated with a iiexible stiiening medium and then coated with a flexible varnish. In the practice of my present invention, this general procedure is adhered to,

yet the body portion of the resultant instrument may be caused to embody a flexibility in the forward or other section thereof which is to a predetermined extent appreciably greater or less than the flexibility in an adjacent section.

This new result and its corresponding advantages may be accomplished in the manner illustratively exemplied in the accompanying drawings, in which:

Figure l is a perspective view of a typical catheter-type instrument;

Figure 2 is an enlarged fragmentary View of a portion of the instrument with the outer coating broken away to reveal the fabric base in the region of the line A--A of Figure 1; and

Figure 3 is a diagrammatic view illustrating the comparative characteristics, as far as flexibility is concerned, of a conventional catheter-type instrument and one which has been constructed in accordance with the present invention.

The features of the invention may best be described by brief preliminary reference to conven-l tional practice.

A fabric base is rst created. Usually, this base assumes the form of an elongated hollow tube, but under certain circumstances it need not have a longitudinal passageway extending through it. This base is formed of intertwined threads of silk, cotton, or synthetic bre, and usually the threads are braided into the desired relationship. Any weaving or other procedure may be resorted to, however, if desired, although braiding machines have proven to be admirably suited to produce a tubular or elongated fabric base of the character required. This base is initially limp in character, and is customarily impregnated with a flexible stiiening medium of suitable composition. Where the base is a tube, the impregnation is carried out while the tube is mounted upon a suitable rod or mandrel. After wiping oli any excess, the mandrelA (if one has been used) is removed and the impregnating medium is caused to harden or cure, either by air drying, or by subjection to a baking procedure or the like. The reinforced and strengthened fabric base is then subjected to a series of operations during which a flexible tough varnish coating is applied to it; layer by layer, the successive coatings being cured by baking or analogous procedures. After the desired coating has been forme-d, it is burnished and the instrument is subjected to such other iinishing processes as may be deemed desirable `The forward tip of the instrument may be formed either prior to or after the initial impregnation of the fabric base, depending upon the nature of the instrument, and the kind and shape of tip which it is intended to have. In the case of catheters, the several openings or eyes which characterize these instruments may be formed at or near thev forward tipeither duringthe braiding of the base or'during a subsequent stage of treatment.

Depending upon the nature and size of the threads originally employed in formingtheiabric base, upon the dimensions of this base'and` upon the impregnating and coating .media which are employed, the resultant instrument'will have :a size and flexibility of predetermined 'character'. Heretofore, in an instrumentin which thebody portion is of substantially uniform.'diameter,` the bendability and over-all semi-rigidity hasebeen uniform throughout, being usually determinedrbyl a suitable compromise between the exibility required for any given purpose and the stiiness called for by the well-known method in which the instrument is to be employed.

VIn accordance with my invention, the vessential nature f of the manufacturing process remains unchanged, yet varying degrees of flexibility 'may be imparted to the resultant instrument along its longitudinal axis. For illustrative purposes, I have chosen todescribe and illustratethe manner in'which a catheter maybe causedto have an appreciably increased flexibility in its forward region adjacentfto the tip,was compared with the exibility and rigidity of the remaining main portion thereof.

V"Ihus, inlFigure .1, Iha-ve illustrated aV catheter HJy in' which the region forwardly of the dot-'anddash line A'has been caused to embody a greater flexibility-than the 'remaining main portion of the catheter.

The procedurefollowed in accordancewithl the present invention is illustrated inFigure '2, which shows the-structure-inthe vicinity'ofthe dotand-dash lineiA-a'A. Theinitially lim-p fabric base tube t3' is `so. braided or 'otherwise formed that the threads in one region areintertwined in an appreciablylooser'relationship than in-a longitudinally-adjacent region; the exibilities of the corresponding sections of the instrumentbeing correspondingly affected. Initheillustrated embodiment of the invention, I Ahave shown the threads in the region'rearwardlyA of the lineA-A more closelyintertwinedl than in` the'region for- Wardly of this line, whereby the flexibility on' the rear'region is less-than that of the forward'region. Where'the tube is' for-med by'means of' abraiding machine, this result can bebrought about `by adiustments of 'the braiding machineduring the v coarse of its operation.

'The'base'thusformed isL impregnated with a exible stiffeningmediumywhich may be, rfor example,v of thegeneral type in which a suitable carriersuch as tung oil isvassociated with a resin or' resins of polymerizable typeytogether with' a plasticizer'lor other customary ingredients. There are numerous'resins whichican be employed; and among them rare, :for example, `resins of the phenolictype. VThe plasticizer usedmay'be.. any

of the ususal ones, such asl castor oil, 'idibutyl p'hthallate, tri-cresyl-phosphate; and: the like.

In practice, the tube may bemountedzon-a lsuitable rod or mandrel. (-notzshown) eitherbefore tir-after. .the -forward tip isformed, and ymay then be' dipped/into the-impregnating medium. The excess isltheniwiped off, the rod or mandrel is withdrawn. and the impregnated tubefmayrbe placed in a suitable oven to bring about a curing of the impregnating medium.

Subsequently, the tube is handled in the usual fashion to form on it the outer coating i4 of flexible-varnish, whichmay befcomposed, for example, of a tung'oil base, a phenolic orfothersuitable resin, and a plasticizer. This outer coating pro- --duces a tough exible lm having a smooth glossy `surfaceand.resistant to water, body fluids generally, landstandard types of sterilization.

Thebasic difference between the instrument of Figurev 1 andthesordinary type of instrument is indicated diagrammatically in Figure 3. If the ordinary catheter I8 is pressed endwise against -anabutment wall I9, by pressure exerted in the direction indicated by the arrow 2D, it will buckle 'throughoutits' length. On the other hand, if the instrument I0 in Figure 1 is similarly pressed against an abutment I9 by a similar pressure exerted along the direction of the arrow 2|, it will buckle: in the vforward region of greateriexibility but nototherwise. Accordingly-when the instrument lil is inserted into and advanced through one of the ureters or through any other similar constricted body canal, it will feel its way more easily past the curvatures encountered, and'this makes the operationf-safer'and simpler.

While I-havel illustrated a catheter, it will be understood that the invention is equally lapplicable to any catheten-type instrument, whether hollow or not; 'andwhile I have chosen to illustrateI the manner in whichthe forward region of the instrument may be mademore flexible than the balance, it will be understood that other relative exibilities maybe'produced, depending upon particular requirements.

In general it will be understood that'the details herein described and illustratedto explain the general'nature and objective of the invention may readily'be modified by those-'skilled in the art withoutdepartingfrom thef spirit and scope of theinvention as expressed inthe appended claims.

Having thus described my invention and illustrated its use, what I claim'as new and desire to' secure'sby Letters Patent is:

1. In an elongatedexible catheter-type instrument; a fabric base formed of intertwined'threads, the threads in one region of said base being intertwined in an appreciably looser relationship than in a,longitudinally-adjacent region thereof, vthe flexibilities of the corresponding sections ol' the instrumenttbeing correspondinglyl aft acted.

2. Inan elongated flexible cathetertypeinstrument, an.initia1ly limp fabric ibase impregnated withv a flexible stiffening medium and coated with a lexble varnish; the threads in one'region of said base being intertwined in an zappreciably looser relationship than in a longitudinally-adjacent region thereof, the exibilities of thecorresponding sections ofthe 7instrument being correspondingly aected.

LOUIS H. KRIPPENDORF.

REFERENCES CITED The following references are of record inthe file of this patent:

UNITED STATES' 'PATENTS Number Name Date 757,877 Bosch Apr. 19, 190.4

.1,776,879 Baekeland Sept. 30, 1930 2,437,542 Krippendorf Mar. 9, 1948 

